Multichamber mill for grinding materials of all kinds



May 29, 1928.

J. IHLEFELDT MULTICHAMBER MILL FOR GRINDING MATERIALS OF ALL KINDS Filed March 4. 1927 Patented May '29, 1928.

JOHANNES I HLEFELDT, F DESSAU, GERMANY.

MUL'IICHAMLBER MILL FOR GRINDING MATERIALS 0]! ALL KINDS.

Application filed 1mm 4, 1927. Serial No. 172,871.

The invention relates to a multi-chamber 4 mill for grinding materials of all kinds, as

for example cement, limestone, coal,- carbide and the like. the multi-chamber mills in use at present is such, that the balls contacting with the lower portion of the ascending surface of the drum shell are, owing to their centrifugal force, lying upon and pressing it until they will separate from it when having reached a certain height and will fall down in a rojectile-like motion on the remaining grin ing bodies, or on the drum shell respectively. The material to be ground is broken to pieces by the grinding bodies falling down upon it, the effect being that the pieces are thrown about in all directions and are finally received in hollow spaces between adjacent groups of balls. Now, experience has disclosed the fact that the pieces formed by the striking-down of the balls upon the material, are detrimental to the fineness of the material for the reason that-the small pieces, as well as larger ones will find access into the slits of the intermediate plate and from here into the next chamber, without having been ground to the fineness-required for this chamber. Besides, this possibility is favored by the fact that the slits and apertures of the individual intermediate walls are distributed more or less equally over-the several walls.

My invention obviates the disadvantages inherent to the usual construction by provlding segment-shaped apertures extending for some length essentially in proximity to the interior periphery of the drum in such a manner that the aperture in each partition will be staggered with respect to the aperture in the neighbouring partition wall. According to my invention, in addition to this, the apertures are provided with grates which referably may be made adjustable and exc angeable andin some cases also be provided with lifting shovels.

Also, constructions have been proposed having apertures in'the partition walls between the several compartments, said apertures being so arranged that the aperture of one partition wall is sta red with respect to the apertureof the neig bouringpartition wall (see for instance French Patent 461,-

' 129). This construction, however, has the disadvantage that these apertures are of relatively small width near the periphery and in addition to this extend as far as to The method of working ofthe axis of the drum. This construction furthermore has the disadvantage, that material will pass from one compartment into the neighbouring compartment too closely to the axis of the drum, whereby this material is not sufiiciently finely ground when passing into the subsequent compartment of the drum.

The invention is illustrated diagrammaticallyand by wayof example on the accompanymg drawing, on which Figure '1 is a longitudinal section through a mill designed according to this invention, and Figures 2, '3, 4 and 5 are details, all as fully described hereinafter.

- On the drawing a, Fig. 1, denotes the body of the mill; 6 are intermediate walls. the outlet apertures c of which are arranged alternately according tothis invention. This arrangement of the outlet apertures c in the several intermediate 'walls I) is rendered possible, for instance, thereby that the apertures .are combined in the shape of segments. .In Fig. 2 the segment 0 is located in the upper part of the wall. With the next wall the segment 0 lies in the lower part'as in Fig. 3. In Fig. 4 the segment is shut up by some grate bars 7", in order to separate the different kinds of inding bodies. These bars may be adjusta lo and (or) exchangeable. rial to be groun gets into the next following grinding chamber with the aid of shovels g directed correspondingly and how it is distributed over the material already present therein, as well as over the balls.

I- claim:

' 1. A multi-chamber mill comprising in combination, a longitudinal rotatory casing, partition walls subdividing said easing into compartments, said partitlon walls having segment-shaped apertures extending for some length essentially in proximity to the interior periphery of said casing for letting the material pass through from one compartment intothe next and so on, the aperture ineach of said partition walls being staggered withrespect to the aperture in the neig bouring partition wall.

2. A multi-chamber mill'comprising in combination, a longitudinal rotatory casing, partition walls subdividing said easing into compartments, said partition walls having segment-shaped apertures extending for some length in proximity to the interior pe riphery of said casing and adapted tolet the Fi 5 shows how the matematerial pass through from one compartment into the next and soon, and grates in said apertures, the aperture in each of said partition walls being staggered with respect to the aperture in the neighbouring partition Walls.

3. A multi-ehamber mill comprising in c0mbination, a longitudinal rotatory casing, partition walls subdividing said easing into compartments, said partition walls having apertures adapted to let the material. pass through from one compartment into the next and so on, the aperture in each of said partition walls being staggered with respect to the aperture in the neighbouring parti- 15 tion wall, and exchangeable grates provided within said apertures.

In testimony whereof I aflix my signature.

J OHANNES IHLEFELDT. 

